JPH0218931B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a tip for a pipe-type ballpoint pen, in which a metal pipe is processed and used as a tip.

Superior wear resistance compared to synthetic resin chips,
In addition, the use of metal pipes as a material for chips has become mainstream in recent years because they are easy to form, but even though it is easy to form, it is still easier than cutting something made of the same material. However, the shapes of the chips made, especially the shape of the center hole, tend to be simple, and there are also variations in the dimensions of the pipes themselves, resulting in ink flow (a phenomenon in which ink flows backwards into the ink chamber). There are still various issues that need to be improved, such as problems related to ink ejection such as ) and problems with noise (noise that occurs when writing) due to unnecessary movement of the ball within the ball holder.

Some of the above problems can be solved or reduced by structural approaches, such as using the tip of a thin synthetic resin rod inserted into the center hole of a pipe-shaped chip as a ball catch, but to a lesser extent. If the shape of the center hole of the chip could be made as complex as the various ideas known for synthetic resin chips, and if it could be easily processed to make it more complicated, then the material of the metal chip could be brought out even more. Become.

The present invention has been made from the above point of view, and the gist thereof is to provide a gap between a center pin having a concave portion formed in the peripheral wall of the leading end and a plurality of rollers arranged to be rotatable around the center pin. The tip of a metal tip pipe body is inserted into the center, and the tip of the inserted tip pipe body is plastically deformed by the relative rotation of the roller and the tip pipe body, and the center A method for forming a tip for a pipe-type ballpoint pen, characterized in that a convex portion corresponding to a concave portion in the circumferential wall of the pin is formed in the center hole of the tip pipe body.

The following description will be made based on the accompanying drawings. FIG. 1, which shows one embodiment of the present invention, shows that three dot-like protrusions are formed in the center hole of the metal pipe body for chips at the ball-holding part. The pipe body A has the shape shown in FIG.
2 shows a state in which a small diameter portion 3 of a pipe body A, in which an appropriate number of inner protrusions 4 for ball seats or annular shapes are formed, is plastically deformed using a forming tool B.

In the forming tool B, a center pin 5 and three rollers 6 arranged annularly around the center pin 5 are inserted into a concave hole of a fixing member 8 via an outer cylinder 7 (see FIG. 3). ), a cover body 9 is attached to prevent the roller 6 from falling off, and the center pin 5
has three recesses 10 formed at positions 120° apart from each other on the front peripheral wall, and is prevented from falling off by a locking step 11 for the roller 6.

The pipe body A is fixed, for example, by a collect chuck 12 of a lathe, while the fixing member 8 of the forming tool B is also fixed by a drill chuck (not shown), and the pipe body A is rotated. As the forming tool B is pressed, the small diameter portion 3 of the pipe body A is plastically deformed and rolled, and a convex portion 13 is formed in a portion corresponding to the concave portion 10 of the center pin 5. (Of course, the forming tool B side may be rotated, as long as relative rotation is performed.) This is the state shown in Fig. 1, and after this, the pipe is forcibly extracted due to the springback effect. Body A
becomes a chip through processes such as the formation of a small mouth.

As can be seen here, the gap 14 between the center pin 5 and the roller 6 must be sufficient to plastically deform the pipe body A, and in FIG. Although a combination of a center pin 5 having a diameter and a roller 6 having a diameter sufficient to deform the pipe body A from the outside is shown, the main body that deforms the pipe body A is not limited to the roller 6. The center pin 5 may be used instead of the center pin 5, or both may be used. Therefore, the diameters of the center pin 5 and rollers 6 can be appropriately determined as necessary.

Further, the shape of the pipe body A may of course be a pipe body A′ having a simple shape as shown in FIG. As shown in FIG.
An annular recess 10 surrounding the tip peripheral wall of the center pin 52
Their shape and number may be determined as appropriate, such as 2, a combination of these (though not shown), or a structure formed so as to run obliquely on the peripheral wall.

Furthermore, since the pipe body A is made of metal, the protrusion 13 formed on the pipe body A will not completely disappear due to forced removal due to the springback effect, but as shown in FIG. If the center pin 51 is used, it is possible to eliminate the need for forceful punching, but in order to more preferably form the convex portion in the desired shape, a method as shown in FIG. 7 may be used.

That is, the center pin 53 is urged forward by a resilient member 54 such as a coil spring, and after the center pin 53 is first inserted into the pipe body A, the roller 61 is brought into contact with the pipe body A so as to deform it. I will go. This allows the roller 61 to separate from the pipe body A earlier than the center pin 53 during forced removal, and the pipe body A to fully exhibit its own elasticity. Further, the embodiment shown in FIG.
It is also preferable in that the taper angle α of 1 can be made small. This is because the taper angle α sometimes determines the external shape of the pipe body A as a tip, and making the taper angle α small means that the tip can be suitable for diagonal writing. In FIG. 7, reference numeral 55 is a guide for the center pin 53, and reference numeral 56 is a tail plug.

Next, FIG. 8 illustrates that the present invention can be integrated with other forming into the tip of the pipe body A, and FIG. ing. The pipe body A is deformed inward by the rollers 62 to form the mouth portion, and is forcibly pulled out due to the springback effect. Note that reference numeral 57 is a center pin.

Finally, FIG. 9 shows an example of using the pipe body A as a chip. A tip 902 (molded pipe body A) fixed to a tip holder 901 has an ink guiding member 903 made of a fiber bundle, a resin extrusion, a resin sintered body, etc. inserted into its center hole, and A ball 904 is rotatably positioned at the tip. At this time, the convex portion 913 (reference numeral 13 in FIG. 1) serves to prevent the ball 904 from swinging laterally, and also serves to maintain a gap for sufficient ink supply to the tip of the tip.

As explained above, according to the present invention, a desired convex portion can be formed in the center hole of a pipe-shaped chip by the easy method of roll processing, which is highly effective in improving ink circulation and eliminating noise. In addition, it is possible to eliminate variations such as uneven thickness of the pipe body at the time of manufacture, regardless of the manufacturing method such as extrusion or pultrusion. It is extremely useful for manufacturing required ballpoint pen tips.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a main part showing an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view showing an example of a pipe body, FIG. 3 is a cross-sectional view taken along the line - in FIG. 1, and FIG. FIG. 5B is a vertical cross-sectional view showing another example of the pipe body, FIG. 6 is a front view of the main part showing another embodiment of the tip of the center pin, FIGS. 7 and 8 are longitudinal sectional views of the main part showing other embodiments of the present invention, and FIG. FIG. 2 is a vertical cross-sectional view of a main part of an embodiment of a ballpoint pen manufactured in this manner. A...Pipe body, B...Forming tool, 5,51,
52, 53, 57... Center pin, 6, 61,
62...roller, 10,101,102,10
3,104...Concave portion, 13,913...Convex portion.

Claims (1)

[Claims] 1. A center pin with a recess formed in the peripheral wall of the tip,
The tip of a metal tip pipe body is inserted into the gap between a plurality of rollers arranged so as to be able to rotate about the center pin, and the tip of the tip pipe body made of metal is inserted into the gap between the roller and the tip pipe body. The distal end of the inserted tip pipe body is plastically deformed by relative rotation, and a convex portion corresponding to the peripheral wall recess of the center pin is formed in the center hole of the tip pipe body. How to mold the tip of a pipe-type ballpoint pen.